A power semiconductor device is a semiconductor device that may be used as a switch or rectifier for power electronics. For example, a switch-mode power supply (SMPS) often includes one or more power semiconductor switches as a key element in switching operation. Power semiconductor devices, which may be referred to as power devices, are often formed as integrated circuits (ICs) to produce power ICs. The applications of power devices are numerous and advances in technology have further increased the number of possible applications, especially in the field of power ICs.
Power devices are most commonly implemented as power switches in order to operate in either a conduction mode (ON) or a non-conduction mode (OFF). In such applications, power switches are often optimized to operate in either conduction or non-conduction modes, while limiting operation as a power transistor in the linear mode. Often power devices are used to conduct or block a large voltage that is intended to be supplied to a load.
Some common power devices are the power diode, thyristor, power metal-oxide-semiconductor field effect transistor (MOSFET), and insulated gate bipolar transistor (IGBT). The power diode and power MOSFET operate based on similar mechanisms as low power CMOS diodes and MOSFETs, for example, but are able to conduct larger currents and are typically able to support, or block, a larger reverse-bias voltage in the off-state (non-conducting).
Due to the increased current or voltage generally associated with power devices, a power device is often structurally designed in order to accommodate the higher current density, higher power dissipation, or higher breakdown voltage. For example, power devices are often built using a vertical structure and have a current rating proportional to the device's area and a voltage blocking capability related to the height or thickness of the device in the substrate. With vertical power devices, as compared to lateral non-power devices, one of the device terminals is located on the bottom of the semiconductor die.
Power devices often include protection mechanisms to prevent overcurrent or over temperature situations. In certain applications, such protection mechanisms include intelligent elements, such as control and protection circuits, for monitoring and controlling the operation of one or more power devices, such as power switches. Such intelligent elements operate to disable power devices when overcurrent or over temperature occurs. In some situations, existing protection mechanisms may fail to protect switching devices. In various applications, improved protection mechanisms for switching devices are desired.